|
Behavioural Ecology and Evolution of Adaptations Mating systems and life history evolution... 1. Evolution of alternative life histories in bluegill Male bluegill have two discrete life histories that mature at different ages. Female bluegill have a single life history. The blue portions of the arrows represent sexual maturity.
2. Mate choice and genetic benefits in guppies
|
Bluegill males are characterized by a discrete polymorphism in life histories termed "parental" and "cuckolder". In Lake Opinicon, where field research is conducted, parental males mature at about 7 years of age and compete to construct nests in densely packed colonies. Nesting males court and spawn with females and provide sole parental care for the developing eggs and fry in their nests. By contrast, cuckolder males do not build nests of their own or care for their offspring. Cuckolders mature precociously and steal fertilizations in the nests of parental males through two tactics: "sneakers" (age 2-3 years) hide behind plants and debris near the nest edge, but are visible after darting into the nest during female egg releases; "satellites" (age 4-5 years) are about the size of mature females (age 4-8 years) and by expressing female colour and behaviour are able to mislead parental males into identifying them as second females in the nest. Cuckolders die before the age of mature parentals and never become parentals themselves.
Field research on bluegill is conducted every summer at Queen's University Biological Station (QUBS). QUBS is located on the shores of Lake Opinicon, one of the lakes of the Rideau Canal, about 50 km north of Kingston, Ontario. The main facility consists of 32 buildings, including the Operations Centre, a library, conference rooms, lab spaces, a workshop, an aquarium house, and an experimental pool facility. Accommodations range from one-person sleeping cabins to large cottages and dormitory space. Although several of the Station's buildings are original, dating back to the late 1940's, others have been added to provide comfortable accommodations for up to 80 researchers. The station now boasts a fleet of boats, reference collections, and audiovisual, optical and electronic equipment, including an automated weather station. To visit the QUBS website, click here.
Guppies are a small tropical fish native to Trinidad and Venezuela. They have internal fertilization and give birth to live young. Females are highly selective among potential mates even though males provide only sperm and hence genes to the female. Work in my lab has been addressing the potential benefits to female choice in such non-resource based mating systems. My lab has proposed that mate choice by females can increase the genetic quality of their offspring through either GOOD GENES or COMPATIBLE GENES. Good genes have a positive fitness effect independent of the other genes in the genome and consequently have additive genetic variance. In contrast, compatible genes have positive fitness effects only when in a specific combination with other alleles (overdominance) or genes (epistasis) and consequently have non-additive genetic variance. Sexual signals such the orange colouration on the integument of males (see photo) or the courtship display of males may indicate their good gene genetic quality. Odour cues may indicate compatible gene quality at, for example, the genes of the MAJOR HISTOCOMPATIBILITY COMPLEX, which are involved in the immune response and are found in all vertebrates.
|
|
